Research Journal of Applied Sciences, Engineering and Technology 9(10): 895-901, 2015
ISSN: 2040-7459; e-ISSN: 2040-7467
© Maxwell Scientific Organization, 2015
Submitted: December ‎14, ‎2014
Accepted: January ‎27, ‎2015
Published: April 05, 2015
Design of a Secure Smart Grid Architecture Model using Damgard Jurik Cryptosystem
K. Seethal, Divya M Menon and N. Radhika
Department of Computer Science and Engineering, Amrita Vishwa Vidyapeetham, Coimbatore, India
Abstract: Smart grid is a paradigm shift from the traditional Power grid which promises to make the electric grid
both energy efficient and Fault tolerant. Trade-off between Energy savings and Security is a critical issue in Smart
grid architecture. Smart grid architecture requires a high level secure data exchanges between sensors like Phasor
Measurement Units and Advanced Metering Infrastructures like Smart Meters. In this study a Secure Smart grid
Architecture model is proposed for the Smart grid network. Initially DamgardJurik encryption algorithm is applied
on the data from the Phasor Measurement Units and a digital signature is then attached to the encrypted text to
provide further authentication. The digitally signed data is collected in Data centre where it is decrypted. The
proposed architecture has been implemented in both software and hardware. The effectiveness of the system is
verified by introducing an intruder in hardware implementation.
Keywords: DamgardJurik scheme, digital signature, Phasor Measurement Unit (PMU), smart grid
of Smart grid network i.e., Power Generation, Power
Transmission and Power Distribution. Generation Phase
in a Smart grid System does not have any significant
change when compared to Power Grid. The major
concern for security arises at the communication
network deployed in Smart Grid. The Phasor
Measurement Units (PMUs) are measuring equipments
which functions as sensors in the Smart grid
communication network. PMUs require a Coordinated
Universal Time (UTC) which it receives from the
Global Positioning Satellites. Calibrating the time
discrepancies in PMUs is done by Distributed Time
Service (DTS). Coordinated Universal Time (UTC)
generates the voltage and current values. Data
exchanges between the PMUs and PDC that is the
central Data Centre require higher level of security.
Thus this study proposes a Secure Smart Grid
Architecture (SSGA) framework for Smart grid sensor
networks. In particular, this study introduces security
architecture between the distribution and transmission
side of Smart grid while balancing the energy
consumption. Further, detailed results are presented for
security measures adopted between the sensors and the
Data Centre. The major challenge is to ensure high
security with low energy consumption.
The architecture of Smart grid system with three
main modes of operations i.e., Power generation, Power
Transmission and Power Distribution is illustrated in
Fig. 1. This study concentrates on the security aspects
between the Transmission and Distribution side. Here
we have proposed a Secure Smart Grid Architecture
(SSGA) covering these two areas. The study is
organized in the following three sections as: In the
INTRODUCTION
Smart grid has evolved as a powerful replacement
for the traditional electrical power grid in the coming
years. As the need for Electricity increases so is the
need for efficient Power grids. Furthermore the design
of our traditional power grids is not able to meet the
increasing demands of suppliers. Hence we need a
smarter solution and that is Smart grid. The need for an
autonomous, self healing, reliable electric grid has
paved the way for Smartgrid (Rahimi and Ipakchi,
2010). Bidirectional Communication between Power
generation suppliers and end users, deployment of
efficient sensors throughout the network makes the grid
smarter.
Power requirement by the end users and efficient
energy distribution throughout the Smart grid is to be
managed by Advanced Metering Infrastructure (AMI),
without human intervention. Another main component
is the smart meter, which will help the customers to
reduce the energy costs and will automatically turnoff
devices when there is chance for outage.
Another inevitable part of Smart grid is the sensor
network, which consists of a network of sensor nodes
that have processing and routing capabilities of
information. A sensor network monitors the
performance of electronic equipments and generates
billing based on information from smart meters (Yan
et al., 2013).
Smart grid is the need of the century and hence
security is a major concern for the grid. While using
wireless transmission in Smart grid networks high level
of security need to be established at all the three stages
Corresponding Author: K. Seethal, Department of Computer Science and Engineering, Amrita Vishwa Vidyapeetham,
Coimbatore, India
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Res. J. Appl. Sci. Eng. Technol., 9(10): 895-901, 2015
Fig. 1: Smart grid system
following Sections we have considered the related
works in security of Smart grid networks. And we have
described the mathematical background used in this
model. And also formulated the Secure Smart grid
Architecture (SSGA) model in Materials and Methods.
In Results and Discussions we have demonstrated the
results of both software and hardware implementation.
In last Section, we have concluded the paper and
provided directions for future research.
Smart grid is equipped with new technologies day
by day so there arises for security and privacy concerns.
It is so vulnerable and more prone to attacks (Chen
et al., 2012). So our concern is to provide security for
data between transmission and distribution side (Wei
et al., 2009). Fengjun Li, Bo Lu and Peng Liu proposed
(Li et al., 2010) a secure data aggregation model using
Paillier cryptosystem (Paillier and Pointcheval, 1999) in
Smart girds. They have articulated the secure
aggregation using a virtual tree based aggregation of
data. Ye Yan proposed a security protocol which deals
with the Advanced Metering Infrastructure in Smart
grid networks. They have proposed an Integrated
Authentication and Confidentiality (IAC) protocol
which integrates both authentication and confidentiality
for collecting data and messages in a secured way.
Wang and Yi (2011) have analyzed two problems by
creating a wireless mesh network and security
framework under this architecture. Within the network
an intrusion detection security firewall is built and the
network communication architecture is analyzed.
Nicanfar et al. (1999) articulated a mechanism that
utilizes the advances in network in network coding to
maintain data privacy in smart gird through which they
could ensure schemes for encryption and traffic routing.
We need a secure Smart grid system which provides
confidentiality and integrity of data. Therefore we have
implemented Secure Smart grid Architecture (SSGA)
which integrates both encryption and digital signature
to assure security in the Smart grid system between
transmission and distribution side. We used
DamgardJurik cryptosystem (Damgård and Jurik, 2001)
which provides additive property of homomorphic
encryption function.
MATERIALS AND METHODS
Here we discuss the mathematical background of
algorithms used in SSGA model. The main focus is on
DamgardJurik scheme (Damgård and Jurik, 2001) for
encrypting the phasor values. In our Smart grid system
we need to aggregate all the Phasor Measurement Unit
(PMU) values and hence our focus is on homomorphic
encryption. This algorithm uses the property of additive
homomorphism. After applying encryption we are
applying RSA Digital Signature Algorithm to the data
for authenticity.
DamgardJurik encryption scheme:
Definition: Let (M, o) be the message space.
DamgardJurik scheme on M is a quadruple (K g , E p , D c ,
A) which satisfies the following conditions.
Steps involved in key generation: For an input
message DamgardJurik scheme K g will generate a key
pair {k1, k2} where k1→ (n, g) and k2→d:
•
•
•
•
•
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Randomly select two prime numbers p and r which
are independent
Obtain the values for n and λ, where n = pr and
λ = lcm (p-1, r-1)
Choose g = (1+n)j x mod n(s+1), for all g ϵ Z * n (s+1)
Choose b using Chinese remainder theorem where
it should satisfies the conditions b mod n ϵ Z* n and
b = 0 mod λ
Res. J. Appl. Sci. Eng. Technol., 9(10): 895-901, 2015
Fig. 2: Layered architecture of secure smart grid architecture
Steps involved in encryption: Choose a random
number t, where t ϵ Z * n (s+1)
Derive the cipher text c, where, c = gm. tn s mod n (s+1)
Communication Layer which provides secure data
transmission between the physical components through
security algorithms. Layer 3 represents the Application
Layer which manages the information in the data centre
for user specific application.
Here we consider a Secure Smart grid Architecture
model in which there are a number of PMUs attached to
the transmission station. PMUs collect all the Phasor
Measurement values and will transmit it to the
Distribution Controller i.e., Data centre at the
Distribution side. Our model encrypts all the PMU
values before sending to the Data centre using
DamgardJurik Encryption Algorithm. For providing
further authenticity the encrypted data is again digitally
signed using a RSA Digital Signature Algorithm.
Every PMU holds a database for storing voltage
and current values Each Pmu will be having values in
the format Pname*V*V a *I*I a *F# which it periodically
transmits to Data centre. P name defines the PMU name.
V, I, V a , I a represents the voltage, current values and
their angles, respectively. F denotes the frequency. Here
every PMU data is separated using #.
Steps involved in decryption: Compute cb mod n(s+1) to
obtain plain text.
Digital signature: Digital signature is an authentication
for a digital message or document. RSA digital
signature validates the PMU.
Sending process: Create a hash value of the message.
Use private key pair (n, d) to generate the signature.
S = Md mod n.
Sends S to the receiver.
Signature verification: The receiver uses public key
pair (n, e) to obtain the hash value
R = Se mod n
Generate the hash value from the sender’s message
Checks for both hash value
If both values are identical then data will be valid.
Procedure for SSGA software implementation:
1. Read values from serial port.
2. Check for # value.
3. While # do
Read the PMU Name
Choose the DB table corresponding to PMU
name
Insert I and V values to the Database
4. End While
5. For all PMU value in DB table do
Apply DamgardJurik Encryption Algorithm
6. End for
7. Apply RSA Digital Signature Algorithm for the
cipher text
8. end
PROPOSED FRAMEWORK FOR SSGA
Typically any Smart grid application requires a
secure network model for data transmission. The
component of this Secure Smart Grid Architecture
(SSGA) framework includes a Smart grid Generation
Unit, Smart grid Distribution Centre and Transmission
Centre. This architecture proposes a new level of
security between transmission and distribution of Smart
grid system. Therefore we focus on a multi security
system to provide secure data transmission.
Figure 2 depicts a layered visualization of Secure
Smart grid Architecture model (SSGA). Layer 1 is the
Physicallayer
which
represents
the
physical
components involved in SSGA. Layer 2 is the Secure
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Res. J. Appl. Sci. Eng. Technol., 9(10): 895-901, 2015
Fig. 3: GUI of secure smart grid architecture
Fig. 4: GUI of web application of secure smart grid architecture
corresponding database is to be entered. From the GUI
itself one will be able to get the database value.
In our SSGA two options for data storage is
implemented both in database and in website. A
database application and a web application is created to
store these PMU values.
The Web Application is shown in Fig. 4 where the
voltage and current values are stored in web. The Web
Application allows the values to be stored in web.
Administrators can monitor the performance of the
Smart grid by constantly monitoring the PMU Values.
RESULTS AND DISCUSSION
A raw electric system has been made more users
friendly by providing a user interface and efficient ways
to access data from different PMUs. Figure 3 shows the
GUI of Secure Smart Grid Architecture. In the
architectural GUI we have placed bus buttons which are
attached to databases. Whenever values are transmitted
from the Smart grid system it will be stored in the
corresponding database. It identifies the name of the
PMU from the data format and data to the
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Res. J. Appl. Sci. Eng. Technol., 9(10): 895-901, 2015
Fig. 5: Implementation of DamgardJurik Encryption
At the Data centre these values are decrypted and the
frequency value which controls the Smart grid system is
returned to the PMU. The control variable from the
datacenter is also stored in this application for
performance analysis of the Smart grid System. Since it
is decrypted using homomorphic function cipher text
can be used for other operations without revealing the
actual plain text. DamgardJurik scheme uses additive
property of homomorphic function.
The SSGA framework and its methodology are
implemented using DamgardJurik encryption algorithm
and digital signature algorithm. DamgardJurik
algorithm is an additive homomorphic encryption
algorithm which ensures the privacy of encrypted data.
This scheme works well on encrypted data while
maintaining the confidentiality of data. The first step of
our approach is to encrypt the phasor values using
DamgardJurik scheme. Figure 5 shows the stored
values in the PMUs are encrypted using DamgardJurik
Encryption Algorithm.
The sender uses a one way hash function to
calculate the message digest and uses its own private
key to sign the document. The receiver verifies the
signed document with the sender’s public key. Since
the public exponent in the RSA algorithm is smaller
than the private exponent, faster signature verification
is done. Figure 6 shows the verification of digital
signature at the data centre.
Implementation of any encryption algorithms
always gains significance when we provide hardware
implementation for the algorithm. Speed is a major
drawback when running time critical software
implementation.
An
alternative
is
hardware
implementation of encryption algorithms, since
provides speed along with secrecy of the encryption.
In our Secure Smart Grid Architecture (SSGA)
framework we are collecting all the Phasor
Measurement Unit values attached to the transmission
system. PMU is a phasor measurement unit attached to
Smart grid system which measures voltage and current
values periodically. These PMU values are encrypted
using DamgardJurik encryption algorithm. For a higher
level of security we are applying digital signature
algorithm for the encrypted values. A number of PMUs
are connected to each other. Each Pmu will be having
values in the format P name *V*V a *I*I a *F# which it
periodically transmits to Data centre. P name defines the
PMU name. V, I, V a , I a represents the
voltage,899current values and their angles respectively.
F denotes the frequency. Encryption is done for these
values at the sender side (i.e., in PMU) and they are
digitally signed before transmitting to the Data Centre.
At the receiving side these values are decrypted
and the frequency value is used for controlling the
Smart grid system. Depending on frequency values
transmitted from each PMU a control variable is
transmitted from the data centre back to PMU.
dsPIC30F4011 a high-Performance, 16-Bit Digital
Signal Controller is used for our hardware
implementation of the PMU which operates at speed
29.49MHz. This microcontroller is programmed for
encrypting the data using DamgardJurik encryption
algorithm and the data is transmitted to PIC16F877A.
Figure 7 shows the hardware schematic where the 16
bit microcontroller encrypts the data and transmit it to
the datacenter. Zigbee module is used for the wireless
transmission between the PMUs and Data centre. We
have introduced an intruder PC which checks the
security of the SSGA model.
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Res. J. Appl. Sci. Eng. Technol., 9(10): 895-901, 2015
Fig. 6: Digital signature verification
Fig. 7: Hardware schematic for single PMU
The reliability of the implementation has been checked
with an intruder. In our future work, we will employ
Cloud storage for the Data. In the long term we will
also develop a more holistic security model covering
the generation and distribution as well.
CONCLUSION
Security has become a major concern in Smart grid
networks. In this study a Secure Smart Grid
Architecture model (SSGA) was proposed for Smart
grid networks. The security framework for this
architecture is expected to satisfy the security
requirements between the transmission and distribution
side in the Smart grid network. We have applied
DamgardJurik encryption algorithm for providing data
security. To further provide additional security the
encrypted data is again digitally signed using RSA
Digital Signature and finally transmitted to the Data
centre where it’s decrypted. We have carried out both
software and hardware implementations of this model.
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